This invention is directed to a waterborne polymer for dispersing pigments and and in particular to a waterborne acrylourethane polymer used for dispersing pigments in waterbased coating compositions.
Waterbased coating compositions of acrylic copolymer are shown in Wilfinger et al U.S. Pat. No. 4,730,020 issued Mar. 8, 1988. Waterbased dispersions of polyurethanes are known as shown in Drexler et al U.S. Pat. No. 4,489,135, issued Dec. 18, 1984. Coatings of acrylourethane reaction products are shown in Stamegna et al U.S. Pat. No. 4,711,929 issued Dec. 8, 1987. Graft copolymers of acrylic resins having urethane graft components are shown in Simms U.S. Pat. No. 4,243,573 issued Jan. 6, 1981. However, none of the compositions shown in the art suggest a pigment dispersing resin that is useful particularly in waterbased acrylic coating compositions that will adequately disperse pigments in these compositions and be compatible with the acrylic polymers used in these compositions to form high quality exterior original equipment automotive and truck finishes and exterior repair finishes for automobiles and trucks.
For original equipment manufacture of automobiles and trucks and for the repair of damaged finishes of automobiles and trucks, the industry will be using waterbased coating compositions to reduce air pollution. There is a need for a dispersion resin that will be an excellent pigment dispersant for all types of pigments particularly metallic flake pigments and difficult to disperse pigments such as iron oxide pigments and that will be compatible with the film forming binder of the coating composition and will form a high quality, i.e., glossy, durable and weatherable exterior finish for automobiles and trucks.